摘要:

Interpenetrating non-molecular and supramolecular (10,3)-a nets occurring with chiral recognition in crystalline (Ph3MeP)2[NaCr(ox)3] 2 Vanessa M. Russell, Donald C. Craig, Marcia L. Scudder and Ian G. Dance School of Chemistry, University of New South Wales, Sydney 2052, Australia. E-mail: I.Dance@unsw.edu.au Received 13th December 1999, Accepted 28th January 2000, Published 7th February 2000 This report describes the high symmetry cubic crystal structure of (Ph3MeP)2[NaCr(ox)3], in which there is a three-dimensionally non-molecular anionic net of [M(ox)3] sites, interpenetrated by a three-dimensionally supramolecular net of cations, and the enantiospecific relationships between these nets. The anion array is a (10,3)-a net formed by covalent bridging of CrIII and NaI by oxalate anions.The cation array is also a (10,3)-a net where cations are linked by a novel embrace involving phenyl and methyl groups. There are three-fold embraces between the cations and anions, with a calculated attractive energy of 125 kJ mol–1 per Ph3MeP+/[M(ox)3] pair. These embraces are homochiral and provide the chiral recognition between the cation and anion lattices. (Ph3MeP)2[NaCr(ox)3] is distinctive in being the only oxalate-bridged three-dimensional (10,3)-a lattice formed by a monopositive cation. Relationships between (Ph3MeP)2[NaCr(ox)3] and comparable crystals containing [M(bipy)3] or [M(phen)3] cations are described. Amongst crystals with interpenetrating (10,3)-a nets, (Ph3MeP)2[NaCr(ox)3] is a chiral intermediate type with non-molecular··supramolecular nets, between racemic non-molecular··non-molecular nets and racemic supramolecular··supramolecular nets.Individual molecules or ions are capable of participating in more than one embrace, leading to supramolecular arrays in one-, two- and three-dimensions.5–10 These supramolecular nets maintained by weak attractions can be compared and contrasted with the many non-molecular nets where metals are linked by strong covalent bonds through bridging ligands.11–13 b I a One such bridging ligand is oxalate, which forms networks with the general formulae† [M II(ox)3]n2n–, M III(ox) [M 3]n2n– and [MaIIMbIII(ox)3]nn–.14,15 These anionic networks contain metals surrounded by three oxalate ligands, each of which bridges to a neighbouring metal atom.The metal centres are therefore 3-connectors. Compounds containing these networked anions are of current interest due to the possibilities of cooperativity of metal properties, particularly their magnetic and photophysical properties.16–23 The bridging oxalate ligands are good carriers of magnetic interactions between various metal ions.15 There are two distinct arrays formed in these compounds.15,17 One is a planar (6,3) network,19–21,23,24 and the other is a three-dimensional (10,3)-a network.16–18,25,26 The designators (m,n) refer to the smallest cycle in the array (m), and the connectivity at the linkage (n). The planar array is composed of six-membered rings held together by 3-connectors, while the three-dimensional network is made up of ten-membered rings, also held together by 3-connectors.The two networks are shown diagramatically in Fig. 2, where each rod represents an oxalate anion linking two metal centres. The view of the (10,3)-a network is offset slightly in order to show the 10- membered cycle. The (10,3)-a net is cubic, and distinct from but related to12 the tetragonal (10,3)-b net.27 Introduction We are investigating the supramolecular motifs which prevail between molecules or metal complexes where there are phenylated surfaces or heteroaromatic ligands. For cations such as Ph4P+ and Ph3MeP+, the six-fold phenyl embrace [6PE, Fig. 1(a)] occurs frequently.1–3 For tris complexes of the ligand bipyridine, [M(bipy)3]z+, there is formation of the analogous motif, the six-fold aryl embrace [6AE, Fig.1(b)].4 These embraces involve three-fold rotors, and are centrosymmetric or pseudo-centrosymmetric, and so are heterochiral. (a) (b) Fig. 1 (a) The six-fold phenyl embrace (6PE) between a pair of Ph4P+ cations (P purple), and (b) the analogous six-fold aryl embrace (6AE) between a pair of [M(bipy)3]z+ cations (N blue, M orange). Click images for larger view. CrystEngComm, 2000, 3(a) (b) Fig. 2 The two oxalate networks, with each oxalate anion shown as a single rod connecting the two metal centres. (a) The planar (6,3) array and (b) the 3D (10,3)-a array. A representative cycle is numbered in each. These two anion arrays differ also in the chiralities of adjacent metal centres.An [M(ox)3]z– anion has two enantiomers, D and L (see Fig. 3). If adjacent, bridged metal centres are of opposite chirality, the resulting network is the (6,3) layer, while if they have the same chirality, the network formed is the 3D (10,3)-a array. Fig. 4 shows a pair of metal centres of the opposite chirality (a) and a pair of the same chirality (b). L Fig. 3 The [M(ox)3]z– anion in its D and L configurations. D In this paper we describe the crystal structure of (Ph3MeP)2[NaCr(ox)3], which combines the preceding concepts: the crystals contain a non-molecular (10,3)-a net of homochiral M(ox)3 sites, and a supramolecular (10,3)-a (b) (a) Fig. 4 A pair of bridged [M(ox)3] centres of (a) opposite chirality (metal centres differentiated as blue and yellow), (b) of the same chirality (all blue). The metal centres in (a) are coplanar, while those in (b) are clearly non-planar. 2+,3+ net of homochiral Ph3MeP+ cations.The two (10,3)-a nets interpenetrate. This is the first example of the (10,3)-a [M2(ox)3] net crystallised with a monopositive cation: all previous such nets used [M(bipy)3] or [M(phen)3]2+.16– 18,25,26,28,29 In the crystals with these latter cations there is also enantioselective recognition between the molecular cations and the non-molecular lattice of M(ox)3, but the 6AE [Fig. 1(b)] possible between [M(bipy)3]z+ or [M(phen)3]2+ cations does not occur because the cations are too few and dispersed.Results Preparation A solution of K3CrIII(ox)3·3H2O (0.354 g, 0.726 mmol in 15 mL of water) was treated with NaCl (0.056 g, 0.958 mmol in 5 mL of water) and Ph3MePBr (0.473 g, 1.32 mmol in 10 mL of water) dropwise with stirring. The solution obtained was stirred for 15 min and evaporated to approximately half volume to promote precipitation. After two days, dark purple crystals of (Ph3MeP)2[NaCrIII(ox)3] were obtained. The crystals were filtered, washed with water, acetone and ether and air dried. Yield was approximately 50%. The above reaction was repeated under the same conditions but without a source of Na+, i.e. the NaCl was omitted from the reaction mixture and only the K+ from the precursor was present. After evaporation of the solution to half volume no product was obtained over a long period.The solution was then allowed to evaporate to near dryness and the crystals which formed were K3[CrIII(ox)3]·3H2O, the starting material. This indicates that the [KCrIII(ox)3]n2n– network is not formed under the same conditions used to produce [NaCrIII(ox)3]n2n–. For crystallographic details, see Table 1. Energy calculations Intermolecular potentials were calculated by the summed atom··atom potential method,2,31 Etotal = SEijTable 1 Crystal data, data collection and refinement for (Ph3MeP)2[NaCr(ox)3]a Property Formula Formula weight Dimensions /mm Crystal system Space group a/Å V/Å3 Dc/g cm–1 ZmMo/cm–1 2 qmax/° Observed reflections Unique reflections RaRw (C19H18P)2 C6CrNaO12 893.7 0.15 � 0.15 � 0.15 Cubic P213 15.952(2) 4059.2(4) 1.46 44.24 50 932 1326 0.037 0.039 The asymmetric unit consists of one-third of each of two cations and one Cr1/3Na1/3(ox).Each metal and phosphorus atom is located on a three-fold axis. The metrics of the phenyl rings of the cations are known and therefore these rings were treated as rigid groups of mm2 symmetry with the thermal motion of each described by a 12 parameter TL model (where T is the translation tensor, L is the libration tensor).30 The anion atoms and the phorus and methyl carbon atoms were refined anisotropically. Hydrogen atoms of the cations were included in calculated positions and were assigned thermal parameters equal to those of the atom to which they were bonded.The metal–O bond lengths are quite different for the two metal sites. Cr–O = 1.975(3), 1.972(3) Å while Na–O = 2.383(4), 2.402(4) Å. Click here for full crystallographic data (CCDC no 1350/9). where the intermolecular potential for atoms with charges qi, qj separated by dij is given by a a a a )0.5 Eij = eija [(dij/dija)–12 – 2(dij/dija)–6] + qiqj/ edij = r + r ; e = (e e a j i a ij j i dij ij a ij We use a distance dependent permittivity, e = dij. The values of the atom parameters r (Å) and e a (kJ mol–1) are: Ph3MeP+ : Caryl 1.94, 0.33; Haryl 1.62, 0.084; Calkyl 2.04, 0.25; Halkyl 1.62, 0.084; P 2.25, 1.09; [NaCr(ox)3]2– : C 2.04, 0.25; O 1.95, 0.50; M 2.19, 0.84; The atom charges for Ph3MeP+ are Caryl –0.10; Haryl +0.15; Calkyl –0.06; Halkyl +0.07; P +0.40.3]n2n– In selecting atom charges for the anionic [NaCr(ox) net we have been guided by the Mulliken and Hirshfeld apportionment schemes, and the electrostatic potential (ESP) charges, derived from density functional (blyp) calculations on [Cr(ox)3]3– and [Ni(ox)3]4–, and also by the results of calculations by the QEq method.32 The ESP and QEq calculations over-polarise the C–O bonds in oxalate, and therefore the averages of the Mulliken and Hirshfeld charges are used. The derived atom charges are CrIII +0.75; NaI +0.49; O –0.37; C +0.20. This analysis generates charges of MIII +0.74; MII +0.60; O –0.33; C +0.27 for related non-molecular oxalate lattices of the type [M b aIIM III(ox)3]nn–.Description of the structure The crystal lattice of (Ph3MeP)2[NaCr(ox)3] is cubic, with space group P213 which possesses 21 screw axes parallel to the cell edges, and body-diagonal three-fold axes: there are no reflective symmetry elements. Each local Cr(ox)3 and Na(ox)3 unit has exact three-fold symmetry, as do the two independent Ph3MeP+ cations. The anionic array is shown in Fig. 5 which is an all-atom view of the schematic representation in Fig. 2(b). ValueFig. 5 The (10,3)-a network of anions in (Ph3MeP)2[NaCr(ox)3], viewed down the 21 screw axis. Cr atoms are blue, Na are yellow. The array of cations in the cavities of this anion network is such that all P···P distances are equivalent, at 5.83 Å.When the cations are represented only by P atoms with these P···P linkages, the result is a second (10,3)-a network (Fig. 6). There is clearly a similarity with Fig. 2(b). The two networks interpenetrate in the crystal lattice, as shown in Fig. 7. There are slight differences between the two networks, evident in Fig. 7, which result from small differences in their dimensions. The anion network has Cr···Na = 5.65 Å, with angles at the Cr and Na atoms of 119.8 and 119.7°, respectively. The metal atom connector sites are essentially planar. In contrast, the connection points in the cation network, with P···P = 5.83 Å and angles at the two independent P atoms of 115.9 and 115.7°, are somewhat more pyramidal.Another difference in the two interpenetrating lattices is their helicity. By tracing aroundFig. 6 The (10,3)-a net of cations represented only by the P atoms and the P···P intermolecular linkages. the four-membered helices in the two lattices, it is clear that they have opposite chirality. The commensurability of the non-molecular anion lattice and the supramolecular cation lattice, evident in Fig. 7, extends also to the filling of space as shown in Fig. 8. The cations fill the cavities in the anion lattice. What is the supramolecular relationship between adjacent cations, which are closer than Ph3MeP+ cations engaged in the familiar 6PE?6,33,34 These cations form a previously unreported embrace, which involves two phenyl rings and one methyl group from each cation.The embrace has two different local components, shown in Fig. 9: (a) two hydrogen atoms, one from methyl and one from phenyl, are both directed towards a single phenyl ring on the other cation, and (b) an offset face-to-face (OFF) interaction occurs between two phenyl rings on adjacent cations [the phenyl rings involved in this OFF are those which are hydrogen donors in (a)]. Two interactions of type (a) combine with one of type (b) to form the full embrace, shown in Fig. 10. The shorter P···P distance relative to the 6PE is due to the smaller methyl group. The calculated energy of this embrace is 13 kJ mol–1 of attractive energy per {Ph3MeP+}2. Fig. 7 The interpenetrating lattices formed by the anions and cations in (Ph3MeP)2[NaCr(ox)3]. Only the metal (blue/yellow) and phosphorus (purple) atoms are shown.The opposite helicities of the two nets can be observed. Fig. 8 (a) Space filling view of the lattice, down c, showing how the cations fit into the spaces left by the anion network. The Cr atoms are blue, Na are yellow. (b) Click on first image or here for a larger view; and on second image or here to access a 3D model of the structure. Each Ph3MeP+ cation (located on a crystallographic threefold axis) is able to engage in three of these embraces, with three different combinations of one methyl hydrogen and two phenyl rings. The triplet of embraces is illustrated in Fig. 11. All the embraces are necessarily identical, and are formed between pairs of crystallographically independent cations.This triplet is the supramolecular 3-connector in the cation net of Fig. 6. What is the supramolecular interaction between the anion and cation networks? The helical three-fold M(ox)3 units and Ph3MeP+ cations are coaxial, and come together such that the three flanges of the M(ox)3 unit and the three phenyl rings of the adjacent cation interlock forming three OFF oxalato···phenyl interactions [Fig. 12(a)]. In addition to these three OFF interactions there are three Hphenyl···Ooxalate hydrogen bonds, shown by the black lines in Fig. 12(b). We call this the threefold embrace, and have calculated that it contributes 125 kJ mol–1 of attractive energy per Ph3MeP+/[M(ox)3] pair for both M = Cr and M = Na.The three-fold embrace links the helicities of the Ph3MeP+ cations and the M(ox)3 units, which must be homochiral.Fig. 11 One central Ph3MeP+ cation forming three identical embraces with surrounding cations, as the 3-connection point for the supramolecular (10,3)-a net. a (a) (b) Fig. 9 (9a) The combination of one Hmethyl and one Hphenyl directed towards a phenyl ring on the second cation. The six Hmethyl···Cring contacts range from 3.0 to 3.6 Å, and the Hphenyl···Cring distances are in the range 2.8 to 3.6 Å; (9b) the offset face-to-face interaction. The distance between the planes of the phenyl rings is about 3.8 Å. (a) b Fig. 12 (a) Spacefilling view of the three-fold embrace between a M(ox)3 subunit and a Ph3MeP+ cation in (Ph3MeP)2[NaCr(ox)3]; (b) the same embrace with the Hphenyl···Ooxalate hydrogen bonds marked in black.Click images for larger view. (b) Fig. 10 The embrace formed between a pair of cations, in (a) skeletal and (b) space filling views. Click images for larger view. Discussion Metal coordination networks of the (10,3)-a and (10,3)-b topologies are known to interpenetrate,12 with up to eight interpenetrating enantiomorphic (10,3)-a nets.35 In these crystals the nets are three-dimensionally non-molecular, and are chemically equivalent and enantiomeric (and therefore the crystals are regarded as three-dimensional racemates). The present compound has two (10,3)-a netsTable 2 Compounds containing the (6,3) oxalate networks Other components Anion [N(Bun)4]+ PPh4+ [N(Prn)4]+ [N(Bun)4]+ [N(pentn)4]+ 5 PhMe3N+, Cl–, 5H2O [MnIICrIII(ox)3]nn– [MnIICrIII(ox)3]nn– [MnIICrIII(ox)3]nn– [MnIIFeIII(ox)3]nn– [MnIIFeIII(ox)3]nn– 2 [NaICrIII(ox)3]n2n– a Reference code in the Cambridge Structural Database.which are different: one is three-dimensionally nonmolecular, and the other is three-dimensionally supramolecular. The chiralities of the non-molecular and supramolecular nets are opposite, but the crystal is not a racemate and has net chirality. The known (10-3)-a [M2(ox)3] nets with dipositive cations are not interpenetrating nets because there are no supramolecular interactions between the cations. The crystal structure of cyanamide, NH2CN, involves racemic interpenetration of two supramolecular (hydrogen bonded) (10,3)-a nets.12 Thus, amongst crystals with interpenetrating (10,3)-a nets, (Ph3MeP)2[NaCr(ox)3] is a chiral intermediate type with non-molecular··supramolecular nets, between racemic nonmolecular··non-molecular nets and racemic supramolecular··supramolecular nets.All previously reported compounds in which [M2(ox)3] anions are crystallised with monopositive cations occur as the 2D (6,3) oxalate networks, previously described [Fig. 2(a)]. These compounds are listed in Table 2. In contrast, all previously reported oxalate anions forming the (10,3)-a network have been crystallised with the cations [M(bipy)3]z+ (z = 2 or 3) or [M(phen)3]2+ (see Table 3).Prior to the present work there was a clear distinction between the two classes in terms of the cations: those with mono-positive cations formed the (6,3) lattices and those with multi-positive cations formed the (10,3)-a lattices. Crystalline (Ph3MeP)2[NaCr(ox)3] described here is the first instance of the (10,3)-a oxalate lattice with a monopositive cation. In order to understand this fully we now analyse details of the structures with the (10,3)-a nets, which are listed in Table 3. 2 b All of the lattices are cubic, with similar dimensions. The homometallic [M II(ox)3]n2n– compounds crystallise in space group P4132 (or its enantiomer, P4332) while the heterometallic compounds [MaIM III(ox)3]n2n– have space group P213. These two space groups are essentially the same.One metal atom type in P213 is located at the 3-fold Table 3 Compounds containing 3D (10,3)-a networks of oxalate anion Other components Anion [NiII(bipy)3]2+ [FeII(bipy)3]2+ [CoIII(bipy)3]3+, ClO4– [CrIII(bipy)3]3+, ClO4– [CrIII(bipy)3]3+, BF4– [Mn2(ox)3]n2n– [Fe2(ox)3]n2n– [Co2(ox)3]n2n– [Mn2(ox)3]n2n– [Mn2(ox)3]n2n– [NaIFeIII(ox)3]n2n– [FeII(bipy)3]2+ [FeII(bipy)3]2+ [FeII(bipy)3]2+ [NiII(bipy)3]2+ [CrIII(bipy)3]3+, ClO4– [CoIII(bipy)3]3+, PF6– [LiICrIII(ox)3]n2n– [AgICrIII(ox)3]n2n– [NaIAlIII(ox)3]n2n– [NaICrIII(ox)3]n2n– [NaICrIII(ox)3]n2n– [KICoIII(ox)3]n2n– [NiII(phen)3]2+, 2H2O [NaICrIII(ox)3]n2n– 2 Ph3MeP+ a Reference code in the Cambridge Structural Database.Refcodea Space group R3c R3c R3c LIDGOU PINFOH RUPBEJ RUPBIN TAWQAJ YOFMAH P63 C2221 P21/c site (x, x, x), while the other is on a second 3-fold site with parameter approximately 3/4-x. In the P4132 structures, these two sites are occupied by the same metal atom type and are equivalent. The variation in the cell dimension for all but the last two compounds in Table 3 is quite small (0.32 Å) and corresponds to variations in the sizes of the metal atoms: it is not affected by the space-group difference, nor by the occurrence of an additional small anion in some of the structures. PNIOCO has a significantly larger value of a (16.23 Å), because it is the only compound containing K (in the anion) and phenanthroline (in the cation), both of which would be larger than their counterparts in the other compounds.The cell in (Ph3MeP)2[NaCr(ox)3] (15.95 Å) is appreciably larger than that (15.52 Å) of the other two crystals with the same anion [NaCr(ox)3]n2n–, which indicates that there is some flexibility in the anion lattice. We attempted, unsuccessfully (see Experimental), to prepare the potassium homolog (Ph3MeP)2[KCr(ox)3] which might suggest that there is a limit to the extent to which the lattice can expand. Enantioselectivity There are two further aspects of these lattices: chiral recognition between the cations and the anionic lattice, and stoichiometry. The M(bipy)3 or M(phen)3 cations in all these oxalate networks are of the same enantiomer (D or L ) as the M(ox)3 anion.The process of crystallisation must be accompanied by chiral recognition and assembly of the anion network with the same local chirality. The reason for this is a three-fold embrace between M(bipy)3 and M(ox)3, similar to that described above for (Ph3MeP)2[NaCr(ox)3]. The threefold flanges of the M(bipy)3 form three OFF interactions with the threefold flanges of M(ox)3, an interlock which ensures the chiral recognition. All anion sites within the network have the same chirality and so all the cations must also have this chirality. Refcodea Space group a /Å P4132 P4332 P4132 P4132 P4132 P213 P213 P213 P213 P213 P213 P213 15.58 15.39 15.29 15.56 15.55 15.51 15.26 15.49 15.52 15.52 15.52 16.23 15.95 HEYTIO YAPPAG PIMYUF ZUQVEM ZUQVIQ HEYTOU HEYTUA TIRHIL TUNFAJ ZUQVAI ZUQVOW PNIOCO This work P213We draw attention to a key difference between embraces adopted by M(bipy)3: the threefold embrace between M(bipy)3 and M(ox)3 is homochiral, while the 6AE [Fig.3 is heterochiral. The 1(b)] between two M(bipy) homochiral embrace uses only OFF local interactions, while the heterochiral embrace uses only edge-to-face (EF) local interactions. Stoichiometry Despite the similarity between (Ph3MeP)2[NaCr(ox)3] and the other structures in Table 3, there is a fundamental difference in stoichiometry, and a consequent difference in the crystal packing.This becomes evident when the sequence along one of the three-fold axes is examined in each type. In the M(bipy)3 templated structures, the arrangement along this axis is shown in Fig. 13. The cation is approximately equidistant from a pair of metal atoms of the anion, and forms the interlocking three-fold embrace analogous to that described above in Fig. 12 with both M(ox)3 groups. However, it is only for each alternate M···M space that a cation is located on the 3-fold axis. In alternate sites, three cations surround the site, interacting in a way (the "bipy box") which will be described below. In contrast, the arrangement in (Ph3MeP)2[NaCr(ox)3] has each M···M space equivalent, even though the identity of the metal atoms alternates along the chain.In each space, there is one Fig. 13 The sequence along the 3-fold axis in [Fe(bipy)3][AgCr(ox)3]25 [TIRHIL]. Cr is blue, Ag is orange. The cations are located approximately equidistant from two metals in the outer segments. There is no cation along the 3-fold axis in the central region, but rather the region is surrounded by three cations. Fig. 14 The sequence along the 3-fold axis in (Ph3MeP)2[NaCr(ox)3] (Cr is blue, Na is yellow). Each metal···metal region is equivalent in terms of its cation occupation. There is one cation located on the 3-fold axis which is surrounded by three more cations to which it forms embraces. For clarity the three surrounding cations are shown only in the central region of the figure. cation on the 3-fold axis and it is surrounded by the three cations with which it forms the embraces shown in Fig.11. The corresponding view of the 3-fold axis is shown in Fig. 14. The "bipy box" An interesting aspect of the packing in [Fe(bipy)3][AgCr(ox)3] and similar compounds is that the set of three Fe(bipy)3 cations surrounding the 3-fold axis (central portion of Fig. 13) form a box,17,18 shown in Fig. 15. The faces of the box are six bipyridine ligands, pairs of which originate from the three different cations. When the metal in the cation is oxidation state III, as in [Cr(bipy)3][CrNa(ox)3].ClO4, the additional anion is located in the centre of the box,17 and therefore the change in formula does not lead to a change in space group or cell dimensions.When only the cation metal atoms and Cl atoms from ClO4– are considered, once again a (10,3)-a network can be constructed from the M···Cl connections. The cations are not in the correct orientation for the formation of 6AE, and there are no good local intermolecular interactions which drive the formation of this "bipy box".Fig. 15 The "bipy box" formed by three M(bipy)3 cations. In the picture on the right the bipy ligand at the top of the box is omitted, revealing how an anion such as ClO4– can be included. In summary: (i) crystalline [Ph3MeP]2[NaCr(ox)3] contains a threedimensionally non-molecular oxalate-bridged lattice with (10,3)-a connectivity; (ii) it also contains a (10,3)-a supramolecular net of Ph3MeP+ cations connected by a novel embrace involving phenyl and methyl groups, with a calculated attractive energy of 13 kJ mol–1; (iii) there are threefold homochiral embraces between the PPh3 sections of the cations and the flanges of the M(ox)3 moieties, comprised of local OFF interactions, with a calculated attractive energy of 125 kJ mol–1 per Ph3MeP+/[M(ox)3] pair; (iv) these three-fold embraces provide the chiral recognition between the cation and anion lattices, and maintain homochiral crystals; (v) [Ph3MeP]2[NaCr(ox)3] is the first (10,3)-a oxalate bridged lattice formed with a monopositive cation: all other crystals with monopositive cations form the alternative 2D (6,3) lattice; (vi) the lattice dimensions and cubic symmetry for [Ph3MeP]2[NaCr(ox)3] are effectively equivalent to those for the previously known crystals with [M(bipy)3] or [M(phen)3] cations; (vii) the supramolecular embraces between cations in [Ph3MeP]2[NaCr(ox)3] are not possible in analogous crystals with [M(bipy)3] or [M(phen)3] cations; (viii) the potassium homolog, [Ph3MeP]2[KCr(ox)3], could not be crystallised; (ix) amongst crystals with interpenetrating (10,3)-a nets, (Ph3MeP)2[NaCr(ox)3] is a chiral intermediate type with non-molecular··supramolecular nets, between racemic nonmolecular··non-molecular nets and racemic supramolecular··supramolecular nets.Acknowledgement Support for this work from the Australian Research Council is gratefully acknowledged. 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Chem., 1991, 95, 3358. 33 C. Hasselgren, P. A. W. Dean, M. L. Scudder, D. C. Craig and I. G. Dance, J. Chem. Soc., Dalton Trans., 1997, 2019. 34 C. Horn, I. G. Dance, D. Craig, M. L. Scudder and G. A. Bowmaker, J. Am. Chem. Soc., 1998, 120, 10549. 35 B. F. Abrahams, S. R. Batten, H. Hamit, B. F. Hoskins and R. Robson, Chem. Commun., 1996, 1313. Paper a909749j Footnote †Henceforth M will be used generically to indicate a metal, and [M2(ox)3] could have a single metal type or two different metals. CrystEngComm © The Royal Society of Chemistry 2000

ISSN:1466-8033    

DOI:10.1039/a909749j

出版商:RSC    

年代:2000

数据来源: RSC